DJ-1 Protein and Its Role in the Development of Parkinson's Disease: Studies on Experimental Models.

DJ-1, also known as Parkinson's disease protein 7, is a multifunctional protein ubiquitously expressed in cells and tissues. Interacting with proteins of various intracellular compartments, DJ-1 plays an important role in maintaining different cellular functions. Mutant DJ-1 forms containing amino acid substitutions (especially L166P), typical of Parkinson's disease, are characterized by impaired dimerization, stability, and folding. DJ-1 exhibits several types of catalytic activity; however, in the enzyme classification it exists as protein deglycase (EC 3.5.1.124). Apparently, in different cell compartments DJ-1 exhibits catalytic and non-catalytic functions, and their ratio still remains unknown. Oxidative stress promotes dissociation of cytoplasmic DJ-1 dimers into monomers, which are translocated to the nucleus, where this protein acts as a coactivator of various signaling pathways, preventing cell death. In mitochondria, DJ-1 is found in the synthasome, where it interacts with the ß ATP synthase subunit. Downregulation of the DJ-1 gene under conditions of experimental PD increases sensitivity of the cells to neurotoxins, and introduction of the recombinant DJ-1 protein attenuates manifestation of this pathology. The thirteen-membered fragment of the DJ-1 amino acid sequence attached to the heptapeptide of the TAT protein penetrating into the cells exhibited neuroprotective properties in various PD models both in cell cultures and after administration to animals. Low molecular weight DJ-1 ligands also demonstrate therapeutic potential, providing neuroprotective effects seen during their incubation with cells and administration to animals.

Unveiling the Role of DJ-1 Protein in Vesicular Storage and Release of Catecholamine with Nano/Micro-Tip Electrodes.

DJ-1 protein deficiency caused by PARK7 gene mutation has been suggested to closely relate to Parkinson's disease (PD), mainly through the attenuation D2 dopamine receptor activity in mice; however, whether or how it affects the vesicular storage and exocytosis of neurochemicals remains unclear. By using electrochemical methods at a single vesicle/cell level with nano/micro-tip electrodes, we for the first time find that DJ-1 protein deficiency caused by PARK7 gene knockout (KO) in mice has little effect on vesicular catecholamine content but significantly prolongs the exocytotic events, especially the closing time of exocytotic fusion pores. Further studies suggest the inhibition of α-synuclein aggregation by DJ-1 protein might be one way that DJ-1 protein acts on neurotransmission. This finding offers the first direct link between DJ-1 protein deficiency and vesicular chemical storage and release of chemicals, providing a new chemical insight into the pathology of PD caused by PARK7 gene mutation.

Complex molecular changes induced by chronic progestogens exposure in roach, Rutilus rutilus.

In our previous study, we measured 0.23-13.67ng/L progestogens (progesterone, drospirenone, levonorgestrel) in natural waters in the catchment area of the largest shallow lake of Central Europe, Lake Balaton. Progestogen contaminations act as potent steroids with mixed progestagenic, androgenic and mild estrogenic effects that is why our aim was to investigate the morphological and molecular effects of mixture of progesterone, drospirenone, and levonorgestrel in environmentally relevant (10ng/L) and higher (50 and 500ng/L) exposure concentrations in common roach, Rutilus rutilus. Steroids (e.g. progestogens) and the protein deglycase DJ-1 chaperon molecule aim the same target molecules in cells, therefore, we hypothesized that a relationship may exist between progestogens and DJ-1. Furthermore, our other aim was to follow the changes of signal molecules of different biological function due to progestogen treatment in serum and brain. Adult roaches were exposed to 10, 50 and 500ng/L of mixture of progestogen for 42 days and their somatic indices (brain-somatic, liver-somatic, gonadosomatic and kidney-somatic) were measured. Vitellogenin (VTG) expression (estrogen effect) or inhibition (androgen effect) in fish is a widely used biomarker so we measured its changes in liver by ELISA. To determine the quantity and to map the spatial distribution of DJ-1 chaperon protein the brain and liver tissues were analyzed by ELISA and immunohistochemistry. Furthermore, we also studied molecular alterations: a) in the serum by measuring cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglyceride concentrations and b) in brain homogenate using a cell stress array kit (26 protein). The somatic index of liver and kidney significantly in all the treated groups, whereas the gonadosomatic index of 500ng/L treated group showed significant decrease compared to control animals. VTG level increased significantly in 500ng/L progestogen treated group. Since the concentration of DJ-1 significantly increased in brain and liver in all progestogen treatment groups, the DJ-1 protein could be able to a more sensitive marker than VTG. Serum LDL and cholesterol levels of exposed fish were significantly decreased. DJ-1 was mediated through the stimulation of the expression of LDL-receptor which facilitates reuptake subsequently. In summary, our observations unfolded new data about molecular alterations induced by the combined action of environmental progestogens. In addition, the DJ-1 chaperon protein as a possible biomarker helped to trace the abiotic chemical environmental contaminations, like progestogens in the freshwater ecosystems.

Stable overexpression of DJ-1 protects H9c2 cells against oxidative stress under a hypoxia condition.

It has been well accepted that increased reactive oxygen species (ROS) and the subsequent oxidative stress is one of the major causes of ischemia/reperfusion (I/R) injury. DJ-1 protein, as a multifunctional intracellular protein, plays an important role in regulating cell survival and antioxidant stress. Here, we wondered whether DJ-1 overexpression attenuates simulated ischemia/reperfusion (sI/R)-induced oxidative stress. A rat cDNA encoding DJ-1 was inserted into a mammalian expression vector. After introduction of this construct into H9c2 myocytes, stable clones were obtained. Western blot analysis of the derived clones showed a 2.6-fold increase in DJ-1 protein expressing. Subsequently, the DJ-1 gene-transfected and control H9c2 cells were subjected to sI/R, and then cell viability, lactate dehydrogenase, malondialdehyde, intracellular ROS and antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) were measured appropriately. The results showed that stable overexpression of DJ-1 efficiently attenuated sI/R-induced viability loss and lactate dehydrogenase leakage. Additionally, stable overexpression of DJ-1 inhibited sI/R-induced the elevation of ROS and MDA contents followed by the increase of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) activities and expression. Our data indicate that overexpression of DJ-1 attenuates ROS generation, enhances the cellular antioxidant capacity and prevents sI/R-induced oxidative stress, revealing a novel mechanism of cardioprotection. Importantly, DJ-1 overexpression may be an important part of a protective strategy against ischemia/reperfusion injury.

Increased Salivary microRNAs That Regulate DJ-1 Gene Expression as Potential Markers for Parkinson's Disease.

Small molecule RNAs (microRNAs) are a kind of endogenous, stable, and noncoding RNA molecule that can regulate the expression of target genes such as DJ-1 at the posttranscriptional level. This study aimed to detect the expression of salivary microRNAs and to discover their value as a salivary potential biomarker for Parkinson's disease (PD). Through a case-control study, RT-qPCR technology was used to detect the expression of miR-874 and miR-145-3p in the saliva of 30 PD patients and 30 healthy volunteers. Then we compared the differences in the expression levels of salivary miR-874 and miR-145-3p between the PD group and the control group and analyzed the correlation between the expression of salivary miR-874 and miR-145-3p in terms of age, gender, disease condition, and disease course. We found that salivary miR-874 and miR-145-3p were both positively expressed in the PD group and control group, and their expression in the PD group was higher than that in the control group. The expression of salivary miRNA-874 and miR-145-3p had no clear correlation to age, gender, total RNA concentrations in saliva, the score of UPDRSII, UPDRSIII, olfactory test scale, MMSE, MoCA, Hohn-Yahr stage and disease course. In conclusion, in the PD group and the control group with positive expression, the expression levels of miR-874 and miR-145-3p in the PD group were higher than those in the control group. The detection of miR-874 and miR-145-3p expression in saliva can be used as an auxiliary biomarker for PD.

Antiapoptotic activity of Chlamydia trachomatis Pgp3 protein involves activation of the ERK1/2 pathway mediated by upregulation of DJ-1 protein.

Chlamydia trachomatis has evolved strategies to prevent host cell apoptosis to evade the host immune defense. However, the precise mechanisms of antiapoptotic activity of C. trachomatis still need to be clarified. Pgp3, one of eight plasmid proteins of C. trachomatis, has been identified to be closely associated with chlamydial virulence. In this study, we attempted to explore the effects and the mechanisms of Pgp3 protein on apoptosis in HeLa cells; the results showed that Pgp3 increased Bcl-2/Bax ratio and prevented caspase-3 activation to suppress apoptosis induced by TNF-α and cycloheximide (CHX) through ERK1/2 pathway activation. Downregulation of DJ-1 with siRNA-DJ-1(si-DJ-1) reduced ERK1/2 phosphorylation and elevated apoptotic rate significantly in Pgp3-HeLa cells. However, inhibition of ERK1/2 signal pathway with ERK inhibitor PD98059 had little effect on DJ-1 expression. These findings confirm that plasmid protein Pgp3 contributes to apoptosis resistance through ERK1/2 signal pathway mediated by upregulation of DJ-1 expression. Therefore, the present study provided novel insights into the role of Pgp3 in apoptosis and suggested that manipulation of the host apoptosis response could be a new approach for the prevention and treatment of C. trachomatis infection.

Oxidative stress and mitochondrial dysfunction-linked neurodegenerative disorders.

Reactive species play an important role in physiological functions. Overproduction of reactive species, notably reactive oxygen (ROS) and nitrogen (RNS) species along with the failure of balance by the body's antioxidant enzyme systems results in destruction of cellular structures, lipids, proteins, and genetic materials such as DNA and RNA. Moreover, the effects of reactive species on mitochondria and their metabolic processes eventually cause a rise in ROS/RNS levels, leading to oxidation of mitochondrial proteins, lipids, and DNA. Oxidative stress has been considered to be linked to the etiology of many diseases, including neurodegenerative diseases (NDDs) such as Alzheimer diseases, Amyotrophic lateral sclerosis, Friedreich's ataxia, Huntington's disease, Multiple sclerosis, and Parkinson's diseases. In addition, oxidative stress causing protein misfold may turn to other NDDs include Creutzfeldt-Jakob disease, Bovine Spongiform Encephalopathy, Kuru, Gerstmann-Straussler-Scheinker syndrome, and Fatal Familial Insomnia. An overview of the oxidative stress and mitochondrial dysfunction-linked NDDs has been summarized in this review.

DJ-1 as a potential biomarker for the development of biocompatible multiwalled carbon nanotubes.

BACKGROUND: In the present study, we investigated whether DJ-1 could serve as a biomarker for assessing the biocompatibility of multiwalled carbon nanotubes (MWCNTs), using the highly purified carbon nanotube, HTT2800. METHODS: Using Western blot analysis, we determined DJ-1 protein levels in two different types of cells (one capable and the other incapable of HTT2800 endocytosis). Using quantitative real-time polymerase chain reaction, we also investigated the ability of purified nanotubes to alter DJ-1 mRNA levels. RESULTS: We demonstrated that the DJ-1 protein concentration was reduced, regardless of the cytotoxic activity of intracellular HTT2800. Furthermore, HTT2800 decreased the DJ-1 mRNA levels in a dose-dependent manner. This decrease in DJ-1 mRNA levels was not observed in the case of Sumi black or cup-stacked carbon nanotubes. CONCLUSION: These data indicate that modification of DJ-1 expression is caused by the cell response to MWCNTs. We conclude that DJ-1 is a promising candidate biomarker for the development of biocompatible MWCNTs.